A computational model for three-note chord(triad)perception called Psychophysical Model of Chord Perception(PMCP)was proposed by Cook and Fujisawa(2006)to quantitatively estimate the listening impression from the acoustic features. We extended this model to four-note chords. In addition, we have validated the results using a listening experiment to evaluate the validity of extending PMCP for triads to four-note chords. The results of factor analysis and correlation analysis on the data obtained from the experiment suggest that the impression of four-note chords are well associated with PMCP, similarly to the cases of triads.

Dementia affects approximately 50 million people worldwide, with projections estimating this number to rise to about 152 million by 2050. In Japan, the prevalence of dementia is particularly high among the elderly, with a certain percentage also exhibiting mild cognitive impairment(MCI). Dementia stems from a variety of underlying diseases leading to higher brain function impairments, encompassing Alzheimer’s disease, vascular dementia, Lewy body dementia, and frontotemporal lobar degeneration, among others. Symptoms of dementia are categorized into core symptoms such as memory disorders, disorientation, and executive dysfunction, as well as behavioral and psychological symptoms like insomnia, wandering, hallucinations, and delusions. Currently, in the absence of definitive treatment drugs, complementary therapy are emphasized, with complementary therapies such as exercise and music therapy showing effectiveness. Specifically, interventions combining exercise and music for healthy elderly individuals as well as those with mild to moderate dementia have demonstrated improvements in cognitive functions and maintenance of daily living activities. Furthermore, with the pandemic of the novel coronavirus, the efficacy of online dementia prevention programs has been explored, observing improvements in specific cognitive functions such as the N-back task. Moreover, systematic reviews on music therapy have confirmed its positive impact on the behavioral and psychological symptoms of Alzheimer’s disease, pointing out the need for further research.

In this paper reviews the development of electronic musical instruments up to recent years, and then discusses the possibility of “co-creation with electronic musical instruments,” which is now beginning as a new development. Electronic musical instruments have evolved to “generate and output sounds electronically” and “simulate and play various musical instruments” to “support a wide range of people who are involved in music”. In the present age, electronic musical instruments may be changing into something that “supports and co-creates users”. From this perspective, this paper introduces the development of new electronic musical instruments.